From 2009 to 2012, Medicare spending grew at an annual rate of 1.1 percent, a decline from the previous five years when Medicare spending increased at an average annual rate of 5.1 percent.

Researchers from Northwestern University’s Kellogg School of Management found 14 percent of the share of the decline in spending growth was due to lingering effects of the U.S. economic recession that lasted from December 2007 to June 2009.

They said that the results showed the economy was not the primary driver for the slowdown in Medicare spending growth and that Medicare spending was less responsive to the macroeconomy compared with private health spending.

If the economy had grown at a normal rate from 2009 to 2012, Medicare spending would have increased an estimated 1.7 percent per year, according to the researchers. They published their findings in the August 2015 issue of Health Affairs.

“Examining this decline by year, we found that the economic downturn had no effect on Medicare spending through 2009 but meaningfully lowered spending growth from 2009 to 2012 by approximately $4 billion,” the researchers wrote. “That amounted to 1.6 percent of Medicare spending in our sample.”

The researchers analyzed data from 2004 to 2012 from the Centers for Medicare & Medicaid Services’ fee-for-service Medicare spending files, which track people who are eligible for fee-for-service Medicare based on their age. They did not include people enrolled in Medicare Advantage.

The researchers mentioned that the economy’s effect on reducing the Medicare growth rate was highest in regions with the highest labor force participation among people older than 65. They added that if the labor participation rate among Medicare eligible people was the same as for people younger than 65, the recession’s effect on spending would have been twice as large.

“Our main analysis found that a 1-percentage-point decrease in the employment-to-population ratio—the percentage of the working-age population that was actually working—would have lowered Medicare spending for 2009–12 by 0.258 percent,” they wrote. “But if seniors had participated in the labor force to the same extent as younger people, the effect would have been a reduction of 0.525 percent in Medicare spending.”